1. Field of the Invention
This invention relates to a method of producing silicone aqueous emulsion compositions having improved adhesion and gloss.
2. Background Information
Due to the superior water repellency, weather resistance and rubbery elasticity of silicones, many silicone aqueous emulsion compositions which form elastomeric materials by the removal of water have been proposed or provided for fiber and paper treatment and for waterproof film-forming materials for concrete, wood, slate, etc.
For example, U.S. Pat. No. 3,004,871, issued Oct. 7, 1961, proposes a composition consisting of a hydroxyl group-terminated diorganopolysiloxane, an organohydrogen polysiloxane, a polyalkylsilicate and an aliphatic acid tin salt. Japanese Patent No. 57-57063 [82-57063] proposes a composition consisting of a hydroxyl group-terminated diorganopolysiloxane, a trifunctional or higher functional silane and an aliphatic acid tin salt. U.S. Pat. No. 4,221,688, issued Sept. 9, 1980, proposes a composition consisting of a hydroxyl group-terminated diorganopolysiloxane, colloidal silica and an aliphatic acid tin salt. U.S. Pat. No. 4,248,751, issued Feb. 3, 1981, proposes a composition consisting of a vinyl-terminated diorganopolysiloxane, an organopolysiloxane containing Si-H groups and a platinum compound U.S. Pat. No. 4,228,054, issued Oct. 14, 1980, proposes a composition obtained from the emulsion polymerization of a cyclic organopolysiloxane and a functionalized organoalkoxysilane.
However, these silicone aqueous emulsion compositions have the drawbacks of a lack of adhesion or of rusting when applied to the metals used in construction, machinery and electrical appliances. As a method for imparting adhesion to silicone aqueous emulsion compositions, Japanese Kokai Patent No. 58-69250 [83-69250] proposes the addition of an amino-functional silane. However, the manufacturing process is overly complicated since it requires the repeated addition of small amounts of the amino-functional silane to a colloidal silica with mixing to homogeneity in order to avoid gelation of the emulsion composition upon the addition of the amino-functional silane. This composition also has the drawback of an inferior surface gloss which degrades the appearance when it is used as a coating agent.
The inventors conducted extensive research to resolve these drawbacks. As a result, the inventors discovered a method for producing a silicone aqueous emulsion composition that would cure at room temperature with the removal of water to form an elastomeric material with a superior surface gloss, good adhesion and good rustproofness.